Method and apparatus for aligning a drill bit over a predetermined point

ABSTRACT

A sight tube is mounted perpendicular to the floor of a portable drilling rig used for drilling earth boreholes and is parallel to and offset from the drilling axis by a predetermined amount. A stake is driven into the earth&#39;&#39;s surface at the predetermined drill point. A sight board having a pivot hole bored through one of its interior portions is pivoted on the stake. A line having a first end anchored near the location of the drilling rig has its other end attached to a first end of the sight board. A sight mark is placed on the second end of the board which is offset from the pivot hole by the same amount that the sight tube is offset from the drilling axis. The driller or rig driver lines the rig up above the line leading to the board by looking through the sight tube and making direction corrections while still a considerable distance from the stake. Thus, the drilling rig is traveling in a substantially straight path as the stake is reached. The rig is driven straight past the stake for the same distance that the sight mark is in front of the drilling axis. The drilling axis is thereby stopped pointing directly toward the stake. Means are provided on the drilling rig to level the floor of the rig with respect to true horizontal to thus enable a true vertical hole to be drilled. Such means include leveling legs which are perpendicular to the rig floor. As the rig floor is lifted, the entire floor swings forward and the sight tube continues to substantially point toward the stake.

United States Patent [1 1 Wyant METHOD AND APPARATUS FOR ALIGNING A DRILL BIT OVER A PREDETERMINED POINT [75] Inventor: Reece E. Wyant, Houston, Tex.

[73] Assignee: Dresser Industries, Inc., Dallas, Tex.

[22] Filed: Aug. 9, 1974 21 Appl. No.: 495,942

Primary ExaminerWilliam D. Martin, Jr. Attorney, Agent, or FirmWilliam E. Johnson, Jr.

[57] ABSTRACT A sight tube is mounted perpendicular to the floor of Aug. 19, 1975 a portable drilling rig used for drilling earth boreholes and is parallel to and offset from the drilling axis by a predetermined amount. A stake is driven into the earths surface at the predetermined drill point. A sight board having a pivot hole bored through one of its interior portions is pivoted on the stake. A line having a first end anchored near the location of the drilling rig has its other end attached to a first end of the sight board. A sight mark is placed on the second end of the board which is offset from the pivot hole by the same amount that the sight tube is offset from the drilling axis. The driller or rig driver lines the rig up above the line leading to the board by looking through the sight tube and making direction corrections while still a considerable distance from the stake. Thus, the drilling rig is traveling in a substantially straight path as the stake is reached. The rig is driven straight past the stake for the same distance that the sight mark is in front of the drilling axis. The drilling axis is thereby stopped pointing directly toward the stake. Means are provided on the drilling rig to level the floor of the rig with respect to true horizontal to thus enable a true vertical hole to be drilled. Such means include leveling legs which are perpendicular to the rig floor. As the rig floor is lifted, the entire floor swings forward and the sight tube continues to substantially point toward the stake.

7 Claims, 7 Drawing Figures ENGINES *g-Af'tNTEBAUGIQIQYS 3 899,833

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36 i I 42K 9 PATENTED AUG 1 9 I975 SEi-IET 3 BF 3 METHOD AND APPARATUS FOR ALIGNING A DRILL BIT OVER A PREDETERMINED POINT BACKGROUND OF THE INVENTION This invention relates to the alignment of the drilling axis of a portable drilling rig in general and specifically to the alignment of a drilling axis of a portable drilling rig with a predetermined point on the earths surface to be drilled.

It is well known in the art of drilling earth boreholes to use portable or mobile drilling rigs in remote locations generally inaccessible by roads and also to use such portable rigs for drilling shallow holes which do not justify the permanent type drilling installations. Oftentimes the exact alignment of the drilling axis with the predetermined point is unnecessary, i.e., drilling within a few feet of the desired point is adequate. However, in drilling the shallow holes, for example, 40 feet, to be used for the pile system for supporting the Alaskan pipeline, the exact location of the pile hole is critical and it has been deemed necessary that a given such hole be drilled within a very few inches of a predetermined spot. Furthermore, these types of portable drilling rigs, especially the track driven vehicles, have steering which is highly insensitive. Also, the nature of these rigs is such that the desired point of drilling cannot be viewed directly because the drill bit and drill pipe must remain suspended in the rigs drill bushing during the alignment process. Furthermore, the pipeline specifications generally require that the drilling rig must be leveled to drill a vertical hole even on a sloping terrain.

It is therefore the primary object of the present invention to provide new and improved methods and apparatus for aligning the drilling axis of a drilling rig with a desired drilling point;

It is also an object of the invention to overcome the previously enumerated problems of the prior art; and

It is yet another object of the invention to provide new and improved methods and apparatus for allowing the operator of a portable drilling rig to drive directly to a predetermined drill point which is not viewable directly.

The objects of the invention are accomplished, generally, by methods and apparatus which utilize a sight tube which is offset from and parallel to the drilling axis by a predetermined amount and which is used to observe a sight mark which is similarly offset from the desired drilling point.

These and other objects, features and advantages of the present invention will be more readily apparent from a reading of the following detailed specification and drawing, in which:

FIG. 1 is a side elevational view of a portable drilling rig which utilizes the method and apparatus according to the present invention;

FIG. 2 is an end elevational view of the apparatus according to FIG. 1;

FIG. 3 is a plan view which schematically illustrates the location of the sight tube in accordance with the present invention and which is offset by a predetermined amount from the drilling axis;

FIG. 4 pictorially illustrates a sight tube and mirror arrangement which is used in accordance with the present invention;

FIG. 5 illustrates the cross hair arrangement located within the sight tube of FIG. 4 takenalong the sectional lines 55; and

FIG. 6 is a pictorial representation of a sight board having a sight mark thereon and which is offset from the .pivot point which coincides with the desired drill point; and

FIG. 7 diagrammatically illustrates the effect of leveling the drilling rig of FIG.s l and 2 to drill a true vertical hole in accordance with the present invention.

Referring now to the drawing in more detail, especially to FIG. 1, there is schematically illustrated a portable drilling rig 10 having track propulsion and being driven by the tracks 1 1. The drilling rig 10 contains the necessary engines within the engine housing 12 for driving the conventional compressors and'fluid circulation devices as well as for providing the power for the mast assembly 13, all of which is well known in the art.

Located within the mast 13 is a chain-driven drill pipe 14 having a drill bit 15 at its lower end. The drilling rig 10 also contains a cab 16 for housing the drilling operator. A fence 17 is partially illustrated for-providing safety for the drilling personnel.

Referring now to FIG. 2, there is illustrated an end view of the drilling rig 10 of FIG. 1. FIG. 2 also illustrates the hydraulic-driven legs 18 and 19 which are used for leveling the floor 20 of the drilling rig to enable the drilling rig to drill a true vertical hole. Although not illustrated except in FIG. 7, one or more such similar leveling legs are provided at the other end of the drilling rig 10.

Referring now to FIG. 3, there is schematically illustrated a plan view of the drilling rig 10. A pair of metal plates 21 and 22 are provided to encircle the drill pipe 14 and thus provide a drill bushing. The drill pipe 14, the drill bit 15 and the metal plates 21 and 22 are located within the square annulus 23 which provides access from above the drilling rig floor to the earth formation to be drilled.

A sight tube 30, illustrated in more detail in FIG.s 4 and 5, is mounted within the annulus 23 and parallel to the axis of the drill pipe 14 which in turn is perpendicular to the floor 20 of the drilling rig. The center point of the cross hairs of the sight tube is offset from the drilling axis of the drill pipe 14 by a predetermined amount, illustrated in FIG. 3 by the dimension d. The sight tube 30, as illustrated better in FIG. 4, has a mirror 31 attached thereto which allows an operator to stand within the cab 16 and visually sight along the length inside the sight tube 30.

Referring now to FIG. 4, the sight tube 30 is illustrated in greater detail. The tube 30 can be easily fabricated from an angle iron bar 32 and a pair of box-like structures 33 and 34 at its upper and lower ends, respectively. A metal plate 35 is attached to the box structure 33 for mounting the sight tube 30 in the manner illustrated in FIG. 3 and a mirror assembly 31 is attached to the plate 35. As illustrated in FIG. 3, the interior of the boxes 33 and 34 can be observed by an operator from the cab 16 and the cross hair assembly 36 can be observed for locating the offset desired drilling point as hereinafter described.

Referring now to FIG. 6, there is pictorially illustrated a sight board 40 having a pivot hole 41 fabricated therein for receiving the drilling stake 42. The drilling stake 42 would normally be driven into the ground in the earth 's surface at exactly the desired drilling point d etermined'by a su rve'y or other means. A

sight mark 43 is located on afirst end of th'eboard 40 and is offset from the pivot hole 41 (and thus the stake 42.) by'a 'predetern'iined amount identified by the numeral -d which" corresponds to .the amount of offset illustrated in FIG, 3. A line 44, fabricated, for example, from wire or string,is attached to the other end of the board 40 away from the'end containing the sight mark 43. The line 44 is anchored at a point 45 some distance away from the board '40,- for example, 100 yards. The a length ofthe line 44 is of no Significance except to allow the mobile drilling rig to line up abov'e'the line' 4 in arriving at the desired drill point.- ln the operation of the embodiments illustrated-i FlG. s::l-6, thestake 42 is driveninto the ground at the desired drillpointlocation in the earths surfaceand the board 40 is pivoted around the stake 42 by placing stake 42 throughthehole'4l in the board 40. The line 44 is then stretched out and anchored at some point 45, perhaps at. the general location of the drilling rig l0,

and the drilling rig is lined up above the length of the line 44 and is driven in the direction of the board 40. As the drilling rig operator drives along the length of the line 44, he lines up the line 44 in the cross hairs 36 within the sight tube 30 by observing the cross hairs 36 V in the mirror 31. By looking through the sight tube, the

operator is able: tomake-direction corrections while still a considerable distance from the stake 42.--:Thus,

the operator. is able to make the drilling rig travel in a substantiallystraight path as the stake 42 is 'ap-" proached. The operator then drives'the rig straight past the. stake 42 untilpthe sight mark 43 is located at the center, point of the 'cross-hairs 36. Since the sight mark 43*Iis offset from the stake 42'by the exact predeter-' mined distance that the sight tube 30 is offset from the drilling axis of the drill pipe 14, then the drill bit is drill a vertical hole along the axis 50 into the earths surface. The rig floor is perpendicular to the drilling axis of the drill pipe 14 and also to the leveling legs 18 and 19 as well as the leg 51 at theother end of the rig.

When the rig floor 20 is leveled (illustrated as 20 ")to obtain an exactly vertical hole, the drill pipe axis continues'to point very closely towards the stake 42 because the legs of the rig are mounted and remain perpendicular to the rig frame'and the pivot points are at the pads located at the lower extremities of the legs 18,--

19 arid 51. Althoughthis cannot be absolutely precise as the vertical projection of the rig length beforeleveling is shorter than the rig length after leveling, the small angles involved make the correction quite small-.Thus,

as illustrated, thesight tube'30 points at the stake 42 in either position of the rig floor 20.-

Thus, it should be appreciated thatlthere have been described herein the preferredembodiments of the] present invention relating to a new and improved method and apparatus for aligning the drilling axisof a portable drilling 'rig over'a desired drill pointin the earths surfacefi-lowever, obvious modifications' 'o'f these preferred'embodiments will occur to those skilled I 4 in' the art; For example, although the preferred embodimerit contemplates a sight tube constructed from a pair of boxes on an angle iron, many forms of such sight tubes areavailable, forexa'mple,'a cylindrical tube.

Likewise, while the preferred embodiment contemplates-that the sight tube is-parallel to, the-drilling. axis, those 'skilled 'in the art will recognize that the intersection of the sight tube axis with the earths surface and the distance that such intersection point is separated from the desireddrill point is lthe criticalfac tor and that the sight tube need not be parallel with the drilling axis. Asone example of this modification, the sight tube can be arranged to have its longitudinal axis intersect the desired drill point; 'In that event,. there is a zero offset andthe sight mark would coincide with the pivotgpoint of the sight board. Quite obviously, however, such .a modification would not work efficiently on unlevel or sloped terrain in such cases where the borehole is to be true" vertical. I I i I f The-embodiments of the invention in which an' 'exc lu sive property orpriv ilege is claimed are defined as fol lows': I 1. Apparatus'for aligning-the drilling axis of a mobile drilling rig with a stake iii the earths surface indicative of the desired drilling location, comprising:

i a sight board'adjacent 'the'earthS surface and'pivotally'attached to said stake, the location 'of said 7 pivot being between the first and second ends of said board, said board having a sight mark on a first end displaced from said pivot'by a predetermined amount a line attached at its first end to the second end of said sight board and anchored at its second end at a remote point'stretched' out along the length of said li'ne;- i i a sight tube mounted on said drilling rig, theprojection of the longitudinal axis of said sight tube intersecting the earths surface at a point displaced from the drilling axisof said drilling rig by the said pre- 1 determined amount; and Y i means to drive said drilling'rig along. said line until said sight tubeis aligned with said sight mark on said sight board. i

2. The apparatus according to claim 1 wherein the longitudinalaxis of said sight tube isparallel to the said drilling axis, 3. In a system for aligning the drilling axis of a mobile drilling rig with a desired drilling location on the earths surface, the improvement comprising: 7

means for establishing a sight I mark adjacent the vi, earths surface which is offset from said drillinglocation by a predetermined amount; and...

sighting means on said drilling rig for sighting said sight mark and having a known spatial relationship to said drilling axis and having asighting axis, whereby the projection of the sighting axis inter- 'sects the'earths surface at a point which is offset from the projection of the drilling axis to the earths surface by said predetermined amount. 4. The system according to claim '3 wherein said sightingaxis is parallel to said drilling axis. 5. A; method of aligning the drilling axis'of a mobile drilling rig-with a desired drilling location on the earth's I surface, comprising: 1' l 1 a establishing a sight mark-adjacent the earths surface which is offset from said drilling location by a predetermined amount; and

moving said drilling rig along a path substantially in alignment with the linear projection of a line having said sight mark and said drilling location thereon until sighting means mounted on said drilling rig are in alignment with said sight mark.

6. The method according to claim 5 wherein the longitudinal axis of said sighting means is parallel with the drilling axis of said drilling rig.

7. In a system for aligning the drilling axis of a mobile drilling rig with a desired drilling location on the earths surface, the improvement comprising:

means for establishing a sight mark adjacent the axis of said sighting means with said sight mark is indicative of the alignment of said drilling axis with said desired drilling location. 

1. Apparatus for aligning the drilling axis of a mobile drilling rig with a stake in the earth''s surface indicative of the desired drilling location, comprising: a sight board adjacent the earth''s surface and pivotally attached to said stake, the location of said pivot being between the first and second ends of said board, said board having a sight mark on a first end displaced from said pivot by a predetermined amount; a line attached at its first end to the second end of said sight board and anchored at its second end at a remote point stretched out along the length of said line; a sight tube mounted on said drilling rig, the projection of the longitudinal axis of said sight tube intersecting the earth''s surface at a point displaced from the drilling axis of said drilling rig by the said predetermined amount; and means to drive said drilling rig along said line until said sight tube is aligned with said sight mark on said sight board.
 2. The apparatus according to claim 1 wherein the longitudinal axis of said sight tube is parallel to the said drilling axis.
 3. In a system for aligning the drilling axis of a mobile drilling rig with a desired drilling location on the earth''s surface, the improvement comprising: means for establishing a sight mark adjacent the earth''s surface which is offset from said drilling location by a predetermined amount; and sighting means on said drilling rig for sighting said sight mark and having a known spatial relationship to said drilling axis and having a sighting axis, whereby the projection of the sighting axis intersects the earth''s surface at a point which is offset from the projection of the drilling axis to the earth''s surface by said predetermined amount.
 4. The system according to claim 3 wherein said sighting axis is parallel to said drilling axis.
 5. A method of aligning the drilling axis of a mobile drilling rig with a desired drilling location on the earth''s surface, comprising: establishing a sight mark adjacent the earth''s surface which is offset from said drilling location by a predetermined amount; and moving said drilling rig along a path substantially in alignment with the linear projection of a line having said sight mark and said drilling location thereon until sighting means mounted on said drilling rig are in alignment with said sight mark.
 6. The method according To claim 5 wherein the longitudinal axis of said sighting means is parallel with the drilling axis of said drilling rig.
 7. In a system for aligning the drilling axis of a mobile drilling rig with a desired drilling location on the earth''s surface, the improvement comprising: means for establishing a sight mark adjacent the earth''s surface having a known relationship to said desired drilling location; a line along which the drilling is to substantially follow in approaching said drilling location, said line including said desired drilling location; and sighting means on said drilling rig having a known spatial relationship to the drilling axis of said drilling rig whereby the alignment of the longitudinal axis of said sighting means with said sight mark is indicative of the alignment of said drilling axis with said desired drilling location. 